The present invention relates to a catalyst for use in the hydrodemetallization (HDM) and the hydroconversion (HC) of heavy crudes and residues and, more particularly, a method for the preparation of the catalyst from natural clay and a process for the treatment of heavy crudes and residues with the catalyst.
The use of catalysts for the hydrodemetallization and the hydroconversion of hydrocarbons of petroleum origin has been known for some time. Known processes are suitable for the reduction of the high metal content, the high asphaltene and Conradson carbon content, the high viscosity and the high sulfur and nitrogen contents of heavy crudes and residues. In addition, these processes are important since they facilitate an increase in yield of liquid fractions which are of greater commercial value.
High metallic contents in crudes and residues are very harmful in other petroleum refining processes, such as hydrocracking, hydrodesulfurization and catalytic cracking, since it poisons the catalysts, while the asphaltenes cause blocking of the catalyst bed thereby reducing its useful life, thus increasing the costs of operation.
Various types of catalysts have been utilized to eliminate metals and asphaltenes contained in heavy crudes and residues. U.S. Pat. Nos. 2,687,985 and 2,769,758 disclose a natural catalyst of the bauxite type. U.S. Pat. No. 2,730,487 teaches the use of a catalyst in which titania is supported on alumina. U.S. Pat. No. 2,771,401 discloses a catalyst formed from artificial or synthetic clays and silica-alumina materials.
U.S. Pat. No. 3,838,042 discloses a catalyst which consists of 0.5% nickel, 1% cobalt and 8% molybdenum, supported on an inorganic polymer obtained by cogelation of an aqueous solution of SiO.sub.2 and Fe.sub.3 and calcination of the gel.
German Pat. No. 2,112,529 teaches a catalyst consisting of a matrix of clay which contains .gtoreq.20 wt.% of Al.sub.2 O.sub.3, as a surface area of 10 m.sup.2 /g, and a pore volume of 0.2 cm.sup.3 /g.
U.S. Pat. No. 3,553,106 utilizes a catalyst of vanadium oxide supported on activated alumina. U.S. Pat. No. 4,075,125 employs as a demetallization catalyst a red mud mixed with Al.sub.2 O.sub.3 (10 wt.%).
German Pat. No. 2,824,765 teaches removing metals and asphaltenes from heavy crude by employing a hydrogenation catalyst which contains magnesium silicate and metals of Group VA, VIA or VIII of the Periodic Table. In addition, catalysts have been described which have one or more metals of Group VIB and Group VIII supported on alumina, which has large pores and a high surface area, able to demetallize heavy crudes, such as U.S. Pat. Nos. 3,876,523, 3,977,961, 3,989,645 and 3,993,601, respectively.
There are a number of disadvantages associated with the known prior art catalysts as set forth above. Many of the catalysts contain large quantities of expensive metals and, therefore, are very costly. The catalysts obtained from natural materials such as bauxite, red med, magnesium silicate, etc. do not specify the degree of dispersion of the metal in the natural material. Finally, all of the above catalysts are employed under extremely severe conditions of pressure and temperature in order to obtain improvement in heavy crudes and residues.
Naturally, it would be highly desirable to provide a catalyst for the hydrodemetallization and hydroconversion of heavy crudes and residues which does not employ the expensive hydrogenating metals.
Accordingly, it is the principal object of the present invention to provide an improved catalyst for use in the hydrodemetallization and hydroconversion of heavy crudes and residues.
It is a particular object of the present invention to provide an improved catalyst for use in the hydrodemetallization and hydroconversion of heavy crudes and residues characterized by improved catalytic activities such as hydrodemetallization and the conversion of asphaltenes and Conradson carbon.
It is a further object of the present invention to provide a method for the preparation from natural clay of a catalyst used in the hydrotreatment of heavy crudes and residues.
It is a still further object of the present invention to provide a process for the treatment of heavy crudes and residues with a catalyst prepared from natural clay.
Further objects and advantages will appear hereinbelow.